Davis & Floyd Water/Wastewater Engineer Presents at SCAPWA

Davis & Floyd water/wastewater engineer Katie McKirahan, PE presented at the South Carolina American Public Works Association (SCAPWA) Conference on June 12th.

She discussed the City of York’s Fishing Creek Wastewater Treatment Plant (WWTP), an ongoing project she is the lead engineer on, while sharing how our firm addresses client needs.

The plant was originally constructed in 1978 and underwent improvements in 2011. These improvements meant to increase the plant’s average capacity from 2 MGD to 4 MGD. However, due to the state of aged equipment, the plant has not achieved this capacity, ultimately hurting the effectiveness of downstream processes.

“Our country is filled with aging infrastructure from roads to water mains to sewers,” comments Katie. “Wastewater treatment plants often fall victim to being overlooked when it comes to divvying out municipal funds. Most plants operate with some success thanks to creative operators who know their plants well and make the most of their aging processes and equipment.”

Receiving a South Carolina Infrastructure Investment Program (SCIIP) Grant of $10 million, the City of York is utilizing it to aid in the completion of this and an additional project.

Needed Improvements for Fishing Creek WWTP

Davis & Floyd has completed the design of improvements that will allow the plant to fully achieve its design capacity of 4 MGD.

These improvements include doubling the capacity of headworks with a new influent bar screen, adding three clarifier mechanisms, and replacing the plant’s sludge dewatering process. The plant currently operates with one clarifier with two original clarifiers that sit abandoned in place. The WWTP requires the capacity of these two clarifiers as well as a fourth clarifier to achieve its 4 MGD capacity.

The sludge dewatering rotary press that was included in the 2011 design will be replaced with a new belt press. This press will be better suited for the capacity that is required and will allow for fewer hours of operation for city staff.

The improvements also include site generators for backup power and will replace all the original aged electrical gear. The project involved bid alternates for additional improvements. These improvements included a new septage receiving station, draining and cleaning of the EQ basin, and a new coarse bubble diffuser system with positive displacement blowers for the existing digesters.

Due to the bidding phase results, these added alternates are not included in the construction plan. However, the city plans to work with Davis & Floyd to pursue these additions as stand-alone projects in the future.



Project Goals and Next Steps

“This project is an example of designing improvements to meet design requirements, address operator/owner concerns, as well as prioritize improvements based on available funding,” shares Katie.

Our team recognized that the focus of the project was listening to the plant operators’ struggles. Through their input, we worked towards removing the causes of recurring problems.

These improvements will increase the plant’s capacity so more screenings are captured at the headworks, reducing problems currently seen downstream. The added clarifier volume will remove current complications of solids excursions, which cause clogging of downstream tertiary filters and non-potable water pumps as well as build up in the chlorine contact chamber. All this requires excessive cleaning. The plant’s reliability will also improve by replacing the old electrical gear and wiring as well as the standby generators. This will provide a robust system that allows the plant to continue treatment even during power outages.

Per the project bid in January 2024, North American Construction Company is the selected contractor. Mobilization will start early summer 2024.